VCSEL with elliptical aperture having reduced rin

ABSTRACT

A VCSEL can include: an elliptical oxide aperture in an oxidized region that is located between an active region and an emission surface, the elliptical aperture having a short radius and a long radius with a radius ratio (short radius)/(long radius) being between 0.6 and 0.8, the VCSEL having a relative intensity noise (RIN) of less than −140 dB/Hz. The VCSEL can include an elliptical emission aperture having the same dimensions of the elliptical oxide aperture. The VCSEL can include an elliptical contact having an elliptical contact aperture therein, the elliptical contact being around the elliptical emission aperture. The elliptical contact can be C-shaped. The VCSEL can include one or more trenches lateral of the oxidized region, the one or more trenches forming an elliptical shape, wherein the oxidized region has an elliptical shape. The one or more trenches can be trapezoidal shaped trenches.

BACKGROUND

Lasers are commonly used in many modern communication components fordata transmission. One use that has become more common is the use oflasers in data networks. Lasers are used in many fiber opticcommunication systems to transmit digital data on a network. In oneexemplary configuration, a laser may be modulated by digital data toproduce an optical signal, including periods of light and dark outputthat represents a binary data stream. In actual practice, the lasersoutput a high optical output representing binary highs and a lower poweroptical output representing binary lows. To obtain quick reaction time,the laser is constantly on, but varies from a high optical output to alower optical output.

Optical networks have various advantages over other types of networks,such as copper wire based networks. For example, many existing copperwire networks operate at near maximum possible data transmission ratesand at near maximum possible distances for copper wire technology. Onthe other hand, many existing optical networks exceed, both in datatransmission rate and distance, the maximums that are possible forcopper wire networks. That is, optical networks are able to reliablytransmit data at higher rates over further distances than is possiblewith copper wire networks.

One type of laser that is used in optical data transmission is aVertical Cavity Surface Emitting Laser (VCSEL). A VCSEL has a lasercavity that is sandwiched between and defined by two mirror stacks. AVCSEL is typically constructed on a semiconductor wafer such as GalliumArsenide (GaAs). The VCSEL includes a bottom mirror constructed on thesemiconductor wafer. Typically, the bottom mirror includes a number ofalternating high and low index of refraction layers. As light passesfrom a layer of one index of refraction to another, a portion of thelight is reflected. By using a sufficient number of alternating layers,a high percentage of light can be reflected by the mirror.

An active region that includes a number of quantum wells is formed onthe bottom mirror. The active region forms a PN junction sandwichedbetween the bottom mirror and a top mirror, which are of oppositeconductivity type (e.g. one p-type mirror and one n-type mirror).Notably, the notion of top and bottom mirrors can be somewhat arbitrary.In some configurations, light could be extracted from the wafer side ofthe VCSEL, with the “top” mirror totally reflective—and thus opaque.However, for purposes of this invention, the “top” mirror refers to themirror from which light is to be extracted, regardless of how it isdisposed in the physical structure. Carriers in the form of holes andelectrons are injected into the quantum wells when the PN junction isforward biased by an electrical current. At a sufficiently high biascurrent, the injected minority carriers form a population inversion inthe quantum wells that produces optical gain. Optical gain occurs whenphotons in the active region stimulate electrons to recombine with holesin the conduction band to the valance band, which produces additionalphotons. When the optical gain exceeds the total loss in the twomirrors, laser oscillation occurs.

The active region may also include an oxide aperture formed using one ormore oxide layers formed in the top and/or bottom mirrors near theactive region. The oxide aperture serves both to form an optical cavityand to direct the bias current through the central region of the cavitythat is formed. Alternatively, other means, such as ion implantation,epitaxial regrowth after patterning, or other lithographic patterningmay be used to perform these functions.

A top mirror is formed on the active region. The top mirror is similarto the bottom mirror in that it generally comprises a number of layersthat alternate between a high index of refraction and a lower index ofrefraction. Generally, the top mirror has fewer mirror periods ofalternating high index and low index of refraction layers, to enhancelight emission from the top of the VCSEL.

Illustratively, the laser functions when a current is passed through thePN junction to inject carriers into the active region. Recombination ofthe injected carriers from the conduction band to the valence band inthe quantum wells results in photons that begin to travel in the lasercavity defined by the mirrors. The mirrors reflect the photons back andforth. When the bias current is sufficient to produce a populationinversion between the quantum well states at the wavelength supported bythe cavity, optical gain is produced in the quantum wells. When theoptical gain is equal to the cavity loss, laser oscillation occurs andthe laser is said to be at threshold bias and the VCSEL begins to ‘lase’as the optically coherent photons are emitted from the top of the VCSEL.

The subject matter claimed herein is not limited to embodiments thatsolve any disadvantages or that operate only in environments such asthose described above. Rather, this background is only provided toillustrate one example technology where some embodiments describedherein may be practiced.

SUMMARY

In one embodiment, a VCSEL can include: an elliptical oxide aperture inan oxidized region that is located between an active region and anemission surface, the elliptical aperture having a short radius and along radius with a radius ratio (short radius)/(long radius) beingbetween 0.6 and 0.8, the VCSEL having a relative intensity noise (RIN)of less than −140 dB/Hz. In one aspect, the VCSEL can include anelliptical emission aperture having the same dimensions of theelliptical oxide aperture. In one aspect, the VCSEL can include anelliptical contact having an elliptical contact aperture therein, theelliptical contact being around the elliptical emission aperture. In oneaspect, the elliptical contact is C-shaped. In one aspect, the VCSEL caninclude one or more trenches lateral of the oxidized region, the one ormore trenches forming an elliptical shape, wherein the oxidized regionhas an elliptical shape. In one aspect, the one or more trenches aretrapezoidal shaped trenches. In one aspect, the VCSEL can include a mesahaving the elliptical oxide aperture, oxidized region, ellipticalemission aperture, elliptical contact, and one or more trenches in theelliptical shape. In one aspect, the VCSEL can include a contact pad andan electrical connector that electrically connects the contact pad withthe elliptical contact.

In one embodiment, a plurality of VCSELs is provided. The plurality ofthe VCSELs can have a normal quantile of at least or about 0.9 (90%) ofthe VCSELs having at least a standard of acceptability. In one aspect,the plurality of VCSELs can include the normal quantile of at leastabout 0.9 (90%) having the RIN of less than or about −141 dB/Hz. In oneaspect, each of the VCSELs of the normal quantile can be on a singlewafer. In one aspect, each of the VCSELs of the normal quantile can havethe elliptical aperture having a short radius and a long radius with aradius ratio (short radius)/(long radius) being between 0.64 and 0.7.

In one embodiment, a method of designing a VCSEL can include: preparinga plurality of VCSELs that each have an elliptical oxide aperture in anoxidized region that is located between an active region and an emissionsurface, an ellipticity of each VCSEL being defined by a short radiusand a long radius of the elliptical oxide aperture with a radius ratio(short radius)/(long radius) being between 0.6 and 0.8, the plurality ofVCSELs having a plurality of different radius ratios; operating theplurality of VCSELs to emit light; testing each VCSEL for its relativeintensity noise (RIN); grouping each VCSEL into a group for a normalquantile of a standard of acceptability; and identifying at least oneradius ratio for a normal quantile group of VCSELs having a RIN lessthan −140 dB/Hz. In one aspect, the preparing includes manufacturing theplurality of physical VCSELs. In one aspect, the preparing includesdigitally creating the plurality of VCSELs to be simulated and theoperating includes simulating emission of light from the plurality ofVCSELs. In one aspect, the normal quantile group is at least or about0.9 (90%). In one aspect, the method can include recording and storingthe identified at least one radius ratio onto a non-transitory tangiblemedium. In one aspect, the method can include recording and storing theRIN and normal quantile for the identified at least one radius ratiointo the non-transitory tangible medium so as to be linked with theidentified at least one radius ratio.

In one embodiment, a method of manufacturing a VCSEL can include:obtaining a radius ratio for an elliptical oxide aperture for a VCSELhaving a relative intensity noise (RIN) of less than −140 dB/Hz;identifying a short radius dimension and a large radius dimension forthe radius ratio; preparing a VCSEL stack of layers; and oxidizing atleast a portion of the VCSEL stack of layers to form the ellipticaloxide aperture within a lateral oxidized region so as to have the radiusratio, short radius, and large radius. In one aspect, the method caninclude preparing and oxidizing a plurality of VCSELs to have theelliptical oxide aperture within a lateral oxidized region so as to havethe radius ratio, short radius, and large radius, the plurality ofVCSELs having a normal quantile of at least or about 0.9 (90%) having orabove a standard of acceptability.

BRIEF DESCRIPTION OF THE FIGURES

The foregoing and following information as well as other features ofthis disclosure will become more fully apparent from the followingdescription and appended claims, taken in conjunction with theaccompanying drawings. Understanding that these drawings depict onlyseveral embodiments in accordance with the disclosure and are,therefore, not to be considered limiting of its scope, the disclosurewill be described with additional specificity and detail through use ofthe accompanying drawings.

FIG. 1 is a schematic of an embodiment of a VCSEL operating environmenthaving an elliptical oxide aperture.

FIG. 2 is a cross-sectional side view of an embodiment of a VCSEL havingan elliptical oxide aperture.

FIGS. 2A-2B are each a top view of an embodiment of a VCSEL having anelliptical oxide aperture.

FIG. 3A is a top view of an embodiment of a VCSEL having an ellipticaloxide aperture and with trapezoidal trenches in an elliptical shape.

FIG. 3B is a cross-sectional side view of a VCSEL having an ellipticaloxide aperture, with trapezoidal trenches in an elliptical shape, andwith an elliptical contact.

FIG. 3C is a cross-sectional side view of a VCSEL having an ellipticaloxide aperture, with metallized trapezoidal trenches in an ellipticalshape, and with an elliptical contact.

FIG. 4 is a top view of an embodiment of a wafer having an array ofVCSELs with an elliptical oxide aperture.

FIG. 5A is a schematic of a cross-sectional profile of an ellipticaloxide aperture.

FIG. 5B includes a graph of the RIN versus normal quantiles for a numberof different VCSELs having different ellipticities.

FIG. 5C includes a graph of the normal quantile 0.90 of RIN fordifferent VCSELs versus the ellipticity.

FIG. 6A is a top view of an embodiment of an elliptical VCSEL.

FIG. 6B is a top view of an embodiment of an elliptical VCSEL with anelliptical mesa.

The elements of the figures are arranged in accordance with at least oneof the embodiments described herein, and which arrangement may bemodified in accordance with the disclosure provided herein by one ofordinary skill in the art. The elements of each of the figures may becombined and arranged with the elements of the other figures.

DETAILED DESCRIPTION

In the following detailed description, reference is made to theaccompanying drawings, which form a part hereof. In the drawings,similar symbols typically identify similar components, unless contextdictates otherwise. The illustrative embodiments described in thedetailed description, drawings, and claims are not meant to be limiting.Other embodiments may be utilized, and other changes may be made,without departing from the spirit or scope of the subject matterpresented herein. It will be readily understood that the aspects of thepresent disclosure, as generally described herein, and illustrated inthe figures, can be arranged, substituted, combined, separated, anddesigned in a wide variety of different configurations, all of which areexplicitly contemplated herein.

Generally, the present advancement in VCSEL technology relates to anoxidized layer having an elliptical oxide aperture. That is, theoxidized layer has an aperture with an elliptical shape, and thereby isreferred to an elliptical oxide aperture. The oxidized region and oxideaperture are commonly used in VCSELs. However, it has been found thatmaking the oxidized aperture in an elliptical shape can providesurprising and unexpected results as described herein, such as improvingthe relative intensity noise (RIN). The oxidized region with theelliptical oxide aperture may be placed within a VCSEL as common inVCSELs, such as between the active region and top mirror. Accordingly,the oxidized layer around the elliptical aperture can provide a blockingregion and the elliptical aperture can provide a conducting region.

The improved RIN can allow for the VCSELs described herein with theelliptical aperture to be used in high speed data links. High speed datalinks can be improved with lower signal to noise ratios. The VCSELs caninclude elliptical current confining apertures for oxide confined VCSELsto lower RIN and improve yield by reducing the across wafer variation ofRIN. The elliptical aperture in the oxidized region introduces asymmetryinto the current injection, and breaks up degeneracy in the modes. Thisstabilizes the mode structure. This in turn translates to lowervariability of RIN in the VCSEL.

The elliptical aperture in the oxide region can be prepared by variousmethods. In one example, the lateral oxidation is used. In anotherexample, the oxidized layer is formed and the elliptical aperture isformed by etching, and then refilling the elliptical aperture with aconductive material.

The elliptical aperture can include a material that is more electricallyconducting than the oxidized material of the oxidized region in theoxidized layer during operation of the VCSEL and light emission in anactive region. Accordingly, the oxidized region and elliptical aperturecan form a heterojunction for selective current guidance. The ellipticalaperture can form a conducting channel through the oxidized region.Planarized layers, such as mirror layers, can be formed over theoxidized layer having the elliptical aperture. Otherwise, the VCSEL canbe prepared as standard in the industry or as in the incorporatedreferences or described herein.

The semiconductor devices of the present invention can be manufacturedfrom any type of semiconductor. Examples of suitable materials includeIII-V semiconductor materials (e.g., prepared from one or more Group IIImaterial (boron (B), aluminium (Al), gallium (Ga), indium (In), thallium(Tl), and ununtrium (Uut)) and one or more Group V materials (nitrogen(N), phosphorus (P), arsenic (As), antimony (Sb), bismuth (Bi) andununpentium (Uup) (unconfirmed)) and optionally some type IV materials.

The semiconductor device can include an active region having one or morequantum wells and one or more quantum well barriers. The active regioncan be configured as any known or developed in the art of VCSELs.

Optionally, electrical confining layers can sandwich the active regionand provide optical gain efficiency by confining carriers to the activeregion. The confining layers can have a region of high energy band gapwhich in many III-V compounds translates to high aluminum content (e.g.,70%-100% Al for the type III material). The aluminum content can beselected to give the material a relatively wide band gap, as compared tothe band gap in the quantum well barriers of the active region. The wideband gap material can give the confining layer good carrier confinementand can increase the efficiency in the active region. In an exemplaryembodiment, the high aluminum region may also include an increase indoping. The confining layer can be doped with a p-type or n-type dopantdepending on whether the confinement barrier is on the n-side or p-sideof the active region.

FIG. 1 shows a planar, current-guided, VCSEL 100 having an ellipticalaperture 129 in an oxidized region 128. The VCSEL 100 can includeperiodic layer pairs for top (124) and bottom (116) mirrors. A substrate114 is formed on a bottom contact 112 and is doped with a first type ofimpurities (i.e., p-type or n-type dopant). A bottom mirror stack 116 isformed on substrate 114 and an optional bottom confining layer 118 isformed on the bottom mirror stack 116. An active region 122 is formedover the bottom mirror stack 116, or over the bottom confining layer 118(when present). An optional top confining layer 120 is formed over theactive region 122. In one optional aspect, the bottom confining layer118 and a top confining layer 120 sandwich the active region 122. Anoxidized region 128 is formed over the active region 122 or over theoptional top confining layer 120. The oxidation region includes alateral oxidized region 127 and a central elliptical aperture 129. Thebottom confining layer 118 and/or top confining layer 120 may be aspacer region between the active region and isolation region.Alternatively, the bottom confining layer 118 and/or top confining layer120 may be a conducting region. Thus, any spacer region bounding theactive region may be a confining region, conducting region, orsemiconductor spacer that is not confining or conducting.

An upper mirror stack 124 is formed over the oxidized region 128. Ametal layer 126 forms a contact on a portion of stack 124, and the metallayer 126 includes an optical aperture, which may be elliptical asshown, but may also be circular. However, other VCSEL configurations mayalso be utilized, and various other VCSEL layers or types of layers canbe used; however, the resulting VCSEL includes an oxidized region havingan elliptical aperture therethrough.

An oxidized region 128 restricts the area of the current flow 130through the active region 122. Oxidized region 128 can be formed toinclude the lateral oxidized region 127 and the elliptical aperture 129by any possible method.

Mirror stacks 116 (bottom) and 124 (top) can be distributed Braggreflector (DBR) stacks, and include periodic layers (e.g., 132 and 134,but may be switched from what is shown). Periodic layers 132 and 134 aretypically AlGaAs and AlAs, respectively, but can be made from otherIII-V semiconductor materials. Mirror stacks 116 and 124 can be doped orundoped and the doping can be n-type or p-type depending on theparticular VCSEL design. However, other types of VCSEL mirrors may beused.

Metal contact layers 112 and 126 can be ohmic contacts that allowappropriate electrical biasing of VCSEL 100. When VCSEL 100 is forwardbiased with a voltage on contact 126 different than the one on contact112, active region 122 emits light 136, which passes through top mirrorstack 124 and out of the optical aperture 125. Those skilled in the artwill recognize that other configurations of contacts can be used togenerate a voltage across active region 122 and generate light 136.

In one embodiment, the oxidized region is formed by selective oxidation,such as lateral oxidation or top down oxidation. The lateral oxidationcan be applied to an elliptically shaped mesa or VCSEL body shape byoxidizing the semiconductor regions to form the elliptical aperture. Thetop down oxidation can be performed after the semiconductor region to beoxidized is formed by applying an elliptical-shaped oxidation resistivecovering and then oxidizing around the elliptical-shaped oxidationresistive covering to sufficiently oxidize the lateral oxidized region.

In one embodiment, any type of chemical vapor deposition can be used todeposit the semiconductor material to be oxidized, then the oxidation isperformed. The elliptical aperture is then etched into the oxidizedregion. The elliptical aperture is then filled with the semiconductormaterial to form the conductive elliptical aperture and lateral oxidizedregion.

The oxidized region can include a single layer as an oxidized layer ormultiple oxidized layers, and/or a single layer elliptical aperture ormultiple layers of central conducting material in the ellipticalaperture.

FIG. 2 illustrates the active region 122 and confining layers 118 and120 under oxidized region 128 having the lateral oxidized region 127 andelliptical aperture 129. The lateral oxidized region 127 forms the outercurrent blocking regions 160, and the elliptical aperture 129 forms thecentral mode confinement region 162. Active region 122 is formed fromone or more quantum wells 138 that are separated by quantum wellbarriers 140, where the optional transition layers may be the linesbetween the quantum wells 138 and barriers 140. The confining layers 118and 120 may optionally include high aluminum content regions 142 and144, respectively. The high aluminum content regions provide goodcarrier confinement in active region 122.

Confining region 120 can include a ramp region 146 that is positionedbetween active region 122 and high aluminum content region 144. Asdiscussed below, the combination of high aluminum content region 144 andthe ramp region 146 provide an injection structure with good carrierconfinement and good electron injection.

Depending on the design of the VCSEL device and the thickness of highaluminum content regions 142 and 144, the confining regions 118 and 120can optionally include spacer layers 148 and 150, respectively. Thethickness of spacer layers 148 and 150 can be dependent upon the kind ofVCSEL device being fabricated. In a vertical cavity resonant device suchas a VCSEL, or VCSEL the spacer layers provide resonant spacing betweenmirrors and provide that the quantum wells of the active region arecentered on a peak of the optical field if desired.

The confining layers 118 and 120 and active region 122 can be formedfrom one or more types of semiconductor materials, such as GaAs, AlAs,InP, AlGaAs, InGaAs, InAlAs, InGaP, AlGaAsP, AlGaInP, InGaAsP, InAlGaAs,SiGe, or the like. Prior to oxidation to form the oxidized region 128may be these same semiconductor materials, which are then oxidized. Assuch, the material in the elliptical aperture 129 may also include thesesame semiconductor materials.

In one example, the lower electrical confining layer is AlInP. Inanother example, the upper electrical confining layer can be AlInGaP.

FIG. 2A shows a top view with a cross-section of an oxidized region 128having the lateral oxidized region 127 and the elliptical aperture 129.This may be a portion of a chip having an array of VCSELs or a singleVCSEL.

FIG. 2B shows a top view with a cross-section of an elliptical mesa 135with shoulders 137. The elliptical mesa may include the oxidized region128 having the lateral oxidized region 127 and the elliptical aperture129

A single chip may have a plurality of VCSELs 100, each having anoxidized region 128 either planar as in FIG. 2A or etched to have aplurality of mesas as in FIG. 2B on a single chip.

In one embodiment, the semiconductor region that is oxidized may beinitially grown or deposited as one or more layers, optionallycontaining some aluminum, and then oxidized to form the ellipticalaperture. In an InP based system, the aluminum content of an acceptablematerial for one or more layers to be oxidized may be about 52 percent.In the GaAs based system such acceptable material for oxidation wouldhave about 97 to 98 percent of aluminum content. The GaAs based layer(s)may be relatively easy to oxidize. The oxidation of such layers may bedone laterally along the side of the device via a trench around thesemiconductor layers and/or with a mesa receiving the lateral oxidation.The process of lateral oxidation may be eased by intentional oxygenincorporation. The oxygen, a water vapor, or other fluid containingoxygen may be used as an oxidizing or diffusing agent that is insertedinto the oxidizing environment and/or layer(s) to oxidize. The term“fluid” may be a generic term which includes liquids and gases asspecies. For instance, water, air, and steam may be fluids.

In one embodiment, the placement of the oxidized region may be at thenode. In one embodiment, a circular aperture of a VCSEL may be replacedwith the elliptical aperture.

FIG. 3A shows a top view of an embodiment of a wafer 300 that includesan elliptical VCSEL 302. The elliptical VCSEL 302 may be configured withlayers as described herein so as to have the oxidized region with thelateral oxidized region with the elliptical aperture therein. The VCSEL302 can include a mesa 304 protruding from the shoulder region 306. Themesa 304 includes the mesa contact 308 (e.g., anode pad), which can be ap-contact (or n-contact when the p/n is swapped). The shoulder 306 caninclude the shoulder pads 310 (e.g., cathode pads), which can ben-contact (or p-contact when the p/n is swapped). The mesa 304 includesthe elliptical aperture 312. The elliptical aperture 312 is surroundedpartially by an elliptical C-shaped contact 314. The elliptical aperture312 and elliptical C-shaped contact 314 are concentrically surrounded bya plurality of trenches 316, which are shown to have a trapezoidalshape. The trenches 316 are used to define the elliptical aperture 312,and allow for the lateral oxidation to form the oxidation region,including the lateral oxidation region and the elliptical aperture 312.The trenches 316 are formed into the epitaxial semiconductor and allowthe oxidizing fluid (e.g., steam) to perform the oxidation. As shown,the trenches 316 are in an elliptical arrangement around the ellipticalaperture 312 and elliptical C-shaped contact 314 with gaps 318 betweenthe trenches 316. Once the elliptical aperture 312 is formed, then themetal for the elliptical C-shaped contact 314 is formed. The mesacontact 308 is connected to the elliptical C-shaped contact 314 by aconductive connector 320.

In one embodiment, the mesa 304 can have a height from the shoulderregion 306 within a range of 5-20 microns, 8-15 microns, or about 10-12microns.

The trapezoidal trenches 316 may be partitioned into two types. Thetrapezoidal trenches 316 are closer to the mesa contact 308 andsurrounded by the conductive connector 320 and may be filled with adielectric material, covered with a conductive material (e.g., metal,conductive connector), and then covered with a dielectric material alongwith the rest of the mesa 304 and optionally shoulder region 306 too.These may be referred to as hybrid trenches 316 a. The trenches 316further from the mesa contact 308 may only be filled with dielectricmaterial and coated with a dielectric material, and thereby aredielectric trenches 316 b.

As shown, the VCSEL 302 includes the mesa 304 and the shoulder region306 separated by mesa sides 330 that slope from the mesa top 332 to theshoulder region 306.

However, it should be recognized that the trenches 316 may be connectedand be an elliptical trench. Also, the elliptical C-shaped contact 314may be a fully ellipse shape. Other variations may be made.

While FIG. 3A shows the ellipticity of the elliptical aperture 312 to beoriented as shown, the ellipticity may be at any angle, such as 45degrees, 90 degrees or other angle in 360 degrees.

FIG. 3B shows a cross-sectional side view of the mesa 304 of the VCSEL302 of FIG. 3A. As shown, the mesa top 332 includes the C-shaped contact314 thereon and lateral therefrom are the trenches 316 b that includesthe trench sides 340 sloped from the mesa top 332 to the trench bottom342. As noted, the trenches 316 b are those without the metal layer. Ascan be seen, the dielectric coating 346 covers the trenches 316 b,C-shaped contact 314 and mesa top 332.

FIG. 3C shows another cross-sectional side view of the mesa 304 of theVCSEL 302 of FIG. 3A that bisects the hybrid trenches 316 a. As shown,the mesa top 332 includes the C-shaped contact 314 thereon and lateraltherefrom are the trenches 316 a that includes the trench sides 340sloped from the mesa top 332 to the trench bottom 342. The metal layer348 of the C-shaped contact 314 is also on the trench sides 340 andtrench bottom 340. The dielectric coating 346 covers the metal layer 348in the trenches 316, C-shaped contact 314 and mesa top 332.

In one embodiment, a single substrate or wafer can include a pluralityof VCSEL emitters, which can be formed into an array. FIG. 4 shows sucha laser array of VCSEL emitters 702 on a single substrate/wafer 700. Itshould be recognized that such a laser array can be arranged with anynumber of VCSEL emitters 702 along rows and/or columns, whether alignedor staggered or in any pattern.

The VCSEL embodiments described herein having the elliptical aperturebound by the lateral oxidized region can provide benefits in reducedRIN. Accordingly, the RIN was studied for such VCSELs with differentelliptical dimensions of the short radius “a” and long radius “b,” asshown in FIG. 5A. Table 1 shows some values for the short radius (a),long radius (b), and the ellipticity (a/b).

TABLE 1 Design a (μm) b (μm) Area: π * a * b (μm²) Ellipticity (E): a/b1 3.5 3.5 38.48 1.00 2 3.1 3.95 38.47 0.78 3 2.8 4.37 38.44 0.64 4 2.54.9 38.48 0.51

FIG. 5B shows a graph that includes a plot of normal quantiledistribution of RIN for VCSELs with different ellipticities. For a RINrequirement of −141 dB/Hz (typical value for PAM4 VCSELs), only 46%percent of the population of circular VCSELs (e.g., a/b=E=1) meet therequirement or are better than the requirement. For elliptical VCSELswith a/b=E=0.64 almost 92% of the VCSELs have a RIN of −141 dB/Hz orlower. This is an increase in yield of 50%.

The data of FIG. 5B allows for enhanced design and manufacturing forVCSELs with elliptical apertures. In one aspect, the design can considerthe desired normal quantile for a suitable distribution of acceptableVCSELs, and then identify the intersection between the normal quantileto the acceptable RIN (e.g., dB/Hz), and select the ellipticity E (e.g.,a/b) that is closest to providing the selected normal quantile with theRIN. For example, 0.92 is a suitable quantile that is an improvementover prior VCSELs, which can be selected for −141 RIN, which then showsthe ellipticity E of 0.64 being selected. In another example, thedesired RIN may be selected and traced to a suitable normal quantile,and then the appropriate ellipticity E is selected. A wafer can then beprocessed to form a plurality of VCSELs therein that will have theselected ellipticity E with the selected RIN with the suitable normalquantile. In another example, the selection of RIN and normal quantilescan show that the range around E=0.64, such as 0.6 to 0.7 may besuitable, or 0.575 to 0.725 may be suitable, or 0.55 to 0.78 may besuitable. However, the value of ellipticity E closer to 0.64 may beoptimal, such as +/−1%, 2%, 3%, 5%, or 10% thereof. It is believed thatbeing able to select the desired RIN and normal quantile to determinethe suitable ellipticity E is surprising and unexpected, and thereby theVCSELs with such an ellipticity have surprising and unexpectedimprovements in function with reduced RIN with increased normalquantiles across a wafer with a plurality of VCSELs or across aplurality of wafers having one or more VCSELs.

In one embodiment, when designing and manufacturing an array of VCSELs,the higher normal quantile is more desirable. As such, a higher normalquantile can be selected, and then the RIN for each ellipticity E can beevaluated to determine the ellipticity for a suitable RIN and theselected normal quantile. As such, normal quantile over or about 0.9,over or about 0.92, over or about 0.95, or over or about 0.98 may bedesirable, with the normal quantile increasing for the number of VCSELsin the array. Accordingly, a plot, table, or other form of data of theRIN versus normal quantile for one or more ellipticities can be used inthe determination of the parameters for the VCSELs, which can then bemanufactured to obtain the array of VCSELs.

In one embodiment, a specific RIN, such as −141 or lower can beselected. Then, a number of different ellipticities can be prepared astest models or prototypes to determine the normal quantile. Thepreferred ellipticity E can then be selected for manufacturing.

FIG. 5C provides a graph of the fit of the value of the 90% quantile forRIN versus ellipticity E. As shown, the minimum of the curve may be thedesired region for ellipticity E. As shown, the range from 0.6 to 0.78is favorable, 0.64 to 0.74 is more favorable, and about 0.7 may be themost favorable. As such, any of these ranges, or E being 0.7+/−1%, 2%,3%, 5%, or 10% thereof may be selected for the ellipticity.

In one embodiment, the short radius (a) may be about 2.8 microns +/−1%,2%, 3%, 5%, or 10% thereof.

In one embodiment, the long radius (b) may be about 4.37 microns +/−1%,2%, 3%, 5%, or 10% thereof.

In one embodiment, a method of selecting dimensions for an ellipticalaperture can be performed. The RIN and normal quantile can be selected,and then the ellipticity is obtained from the data, such as the tablesand graphs herein. The ellipticity is then set and the desired area canbe selected from the data. The area and ellipticity then define theshort radius (a) and the long radius (b). Once the design of thedimensions of the elliptical aperture are determined, the VCSEL ismanufactured accordingly.

In one embodiment, a plurality of different sized areas for theelliptical aperture can be prepared based on the desired ellipticity,and a plurality of ellipticities can be prepared with each set having aplurality of areas. The data can be generated to compare the RIN andnormal quantile in order to provide the tables or graphs for selectingthe value for the ellipticity, short radius a and long radius b, whichis used to then prepare the VCSEL or array of VCSELs.

FIG. 6A shows an elliptical VCSEL 600 a having the elliptical oxideaperture 629 bounded by an elliptical lateral oxidized region 627. Theelliptical lateral oxidized region 627 is bound by an elliptical trench616. However, while the elliptical trench 616 is shown as a continuoustrench it may be divided into one or more distinct trenches with gapsbetween each trench, where optionally, each trench may or may not betrapezoidal as shown in FIG. 3A. Here, the elliptical VCSEL 600 a may bein a chip with or without a mesa, where any mesa may be elliptical or amacro mesa such as shown in FIG. 3.

FIG. 6B shows an elliptical VCSEL 600 b having the elliptical oxideaperture 629 bounded by an elliptical lateral oxidized region 627. Theelliptical lateral oxidized region 627 is bound by an elliptical trench616. However, while the elliptical trench 616 is shown as a continuoustrench it may be divided into one or more distinct trenches with gapsbetween each trench, where optionally, each trench may or may not betrapezoidal as shown in FIG. 3A. Here, the elliptical VCSEL 600 b is inan elliptical mesa 617. The elliptical mesa 617 may also include theelliptical contact, and the contact pad may be on a shoulder (e.g., withthe other contact pads) with an electrical connector therebetween suchas on a mesa side surface.

In one embodiment, a VCSEL can include an elliptical aperture in anoxidized region that is located between an active region and an emissionsurface, the elliptical aperture having a short radius and a long radiuswith a radius ratio (short radius)/(long radius) being less than 1. Inone aspect, the elliptical aperture has a radius ratio of between 0.6and 0.8, between 0.64 and 0.75, between 0.68 and 0.72, between about0.62 and 0.66, or about 0.64 or about 0.70. In one aspect, the VCSELincludes an elliptical emission aperture at or proximal to the emissionsurface. In one aspect, the elliptical emission aperture has a shortradius and a long radius which is the same as the elliptical aperture inthe oxidized region (e.g., elliptical oxide aperture). In one aspect,the VCSEL includes at least a portion of a mirror stack between theelliptical aperture and the emission surface. In one aspect, the VCSELincludes at least a portion of a mirror stack between the oxidizedregion and the emission surface.

In one embodiment, the oxidized region includes a lateral oxidizedregion that is lateral of the elliptical oxide aperture. In one aspect,the lateral oxidized region can have a height that is the same as theheight of the elliptical oxide aperture. In one aspect, the lateraloxidized region can be elliptical, having the elliptical oxide aperturedefined by an elliptical lateral oxidized region.

In one embodiment, the VCSEL includes an elliptical contact having anelliptical contact aperture, the elliptical contact aperture beingaligned with the elliptical oxide aperture, and optionally aligned withthe elliptical emission aperture. In one aspect, the elliptical oxideaperture has a short radius and a long radius that is the same as theelliptical oxide aperture, and optionally aligned with the ellipticalemission aperture. In one aspect, the elliptical contact bounds and/ordefines the area of the elliptical emission aperture, or is +/−1%, 2%,5%, 10%, or 25% thereof. In one aspect, the elliptical contact isC-shaped. In one aspect, the gap in the C-shaped elliptical contact isoriented toward a contact pad, or alternatively is oriented away fromthe contact pad or at any angle relative thereto. In one aspect, anelectrical connector connects the elliptical contact to the contact pad.

In one embodiment, the VCSEL includes one or more trenches locatedaround the oxidized region. In one aspect, the one or more trenches formone or more trenches in an elliptical shape. In one aspect, the one ormore trenches are elliptical trenches. In one aspect, two or moretrenches are arranged in an elliptical shape. In one aspect, the one ormore trenches includes a plurality of trenches one adjacent to the nextin an elliptical circumferential arrangement. In one aspect, each trenchis lateral of the oxidized region.

In one embodiment, the VCSEL includes a mesa having the ellipticalaperture and oxidized region. In one aspect, the active region is in themesa, or it is in a base region under the mesa. In one aspect, thelateral oxidized region is bound by the mesa side surface, which may bevertical or sloped. In one aspect, the mesa includes the ellipticalcontact on the top mesa surface. In one aspect, the mesa includes theone or more trenches around the oxidized region. In one aspect, the mesaincludes a contact pad that is electrically coupled through anelectrical connector to the elliptical contact. In one aspect, the mesais a macro mesa with a cross-sectional profile substantially larger thanthe oxidized region, or than the one or more trenches.

In one embodiment, a plurality of the VCSELs having the ellipticalaperture can have a defined standard for acceptability, wherein VCSELsbelow the standard of acceptability are defined as unacceptable andVCSELs at or above the standard of acceptability are defined asacceptable. In one aspect, the plurality of VCSELs are in amanufacturing lot, wherein the manufacturing lot may be a singleproduction run, a single wafer, a single chip, a single group of singlewafers, a single group of single chips, or the like. In one aspect, thestandard of acceptability is at least the 0.65 normal quantile, at leastthe 0.75 normal quantile, at least the 0.80 normal quantile, at leastthe 0.85 normal quantile, at least the 0.90 normal quantile, at leastthe 0.92 normal quantile, at least the 0.95 quantile, at least the 0.98quantile, or at least the 0.99 quantile.

In one embodiment, a wafer or chip includes a plurality of the VCSELshaving the elliptical aperture and oxidized region. The VCSELs can bearranged in an array. The array of VCSELs may be arranged in alignedrows. The array of VCSELs may be arranged in staggered rows and columns.In one aspect, the wafer or chip is obtained from single production runand thereby considered to be at least one wafer or chip of amanufacturing lot. The wafer or chip may have the standard ofacceptability for all of the VCSELs thereon of at least the 0.65 normalquantile, at least the 0.75 normal quantile, at least the 0.80 normalquantile, at least the 0.85 normal quantile, at least the 0.90 normalquantile, at least the 0.92 normal quantile, at least the 0.95 quantile,at least the 0.98 quantile, or at least the 0.99 quantile. Each VCSEL onthe wafer or chip may have the same dimensioned elliptical oxideaperture. Each VCSEL on the wafer or chip may have the same dimensions:elliptical contact, oxidized lateral region, trenches, one or morecontact pads, mesa, electrical connector, and/or other feature.

In one embodiment, a method of designing a VCSEL having an ellipticalaperture in an oxidized region can be provided. The method can includeperforming a case study of a plurality of VCSELs having differentelliptical aperture cross-sectional profiles, wherein the ellipticalaperture can be the elliptical oxide aperture and/or the ellipticalemission aperture, and wherein the elliptical aperture can be varied inshort radius dimension (a) and/or long radius dimension (b) and/orradius ratio (a/b) also known as ellipticity (E). Each VCSEL of the casestudy may be a simulated VCSEL that is simulated for the case study or aphysical VCSEL that is manufactured for the case study. Each VCSEL ofthe case study is assessed for RIN. Each VCSEL of the case study isassessed for a standard of acceptability. The standard of acceptabilitybeing assessed can include the RIN, short radius, long radius,elliptical cross-sectional area, light emission intensity, lightemission power, data speed, modulation rate, signal to noise ratio, orother. The RIN may be compared to the normal quantile for the VCSELs inthe case study. The RIN for a defined normal quantile (e.g., 0.9) can becompared to the ellipticity (E). The ellipticity E may be selected for adefined RIN (e.g., −141) and a defined normal quantile (e.g., 0.9). Theshort radius dimension and long radius dimension may be defined for theellipticity E. One or more VCSELs, such as an array of VCSELs orwafer/chip with VCSELs, can be manufactured with the selectedellipticity having the short radius dimension and long radius dimensionto have the defined RIN, such that the plurality of VCSELs fall withinthe defined normal quantile for the standard of acceptability.

In one embodiment, a method of manufacturing is provided. The method ofmanufacturing may include obtaining specifications for the VCSEL, whichspecifications include the ellipticity E, short radius dimension (a),and long radius dimension (b) for the elliptical aperture. The VCSEL ismanufactured by preparing a plurality of semiconductor layers thatdefine the features of the VCSEL, such as shown in the figures and/ordescribed herein. The VCSEL can be manufactured to provide the bottommirror, active region, and top mirror with or without any of the otherfeatures. A lower portion of the top mirror adjacent to the activeregion may be oxidized to form the elliptical oxide aperture defined bythe lateral oxidized region. In one embodiment, the VCSEL layers areformed and then one or more trenches in an elliptical shape are formedby etching. The etching can be performed as standard in the art withetch resistive templates being applied to the top of the VCSEL, suchthat etching is performed around the etch resistive templates. The etchresistive templates may define the one or more trenches, and optionally,the mesa. The etching may be performed with the etch resistive templatesin place, and once etching is complete the etch resistive templates maybe removed or additional layers may be deposited thereon. The etchedVCSEL layers may then be subjected to selective oxidation in order toform the oxide region having the elliptical oxide aperture. In oneaspect, an oxidation resistive layer may be applied to the top of theVCSEL layers. In one aspect, an oxidation resistive layer/coating may beapplied into the side walls of the one or more trenches so as to definean oxidation region that does not have any oxidation resistive layer.The oxidation is performed until the desired elliptical oxide apertureis formed within the oxidized region. The oxidation resistive layer maybe removed or it may be included in the VCSEL. Optionally, one or morelayers, such as the top mirror may be formed after the oxidation so asto be located above the oxidized region. The elliptical contact can thenbe formed around an elliptical emission aperture, and where one or moreof the contact pads may be formed. The metal of the elliptical contactmay be connected to the contact pad with or without also covering one ormore trenches (e.g., trapezoidal trenches) or a portion of an ellipticaltrench. A dielectric covering can then be applied to the top region ofthe VCSEL, and may cover the one or more trenches (e.g., fill thetrenches), cover at least a portion of the elliptical contact, cover atleast a portion of a top surface of the VCSEL layers, and either coveror form an emission surface over the elliptical aperture.

In one embodiment, the method of manufacture can include forming theVCSEL layers to include an oxidizable layer (e.g., one or more discretelayers, such as deposition layers). Then, etching the ellipticalaperture into the oxidizable layer and then filling the ellipticalaperture with a non-oxidizable material (e.g., devoid of aluminum).Optionally, one or more trenches are etched, either along with etchingthe elliptical aperture or after the elliptical aperture is filled withthe non-oxidizable material. The oxidizable layer is then oxidized toform the lateral oxidized region. The top layers, such as top mirror,may be formed before or after the oxidizing. Prior to oxidizing, anon-oxidizable layer/coating can be applied as an oxidation resistivetemplate.

It will be appreciated that other methods of manufacturing can beperformed to form the embodiments of the VCSEL having the ellipticaloxide aperture that is described herein.

Common to chemical etching, a mask can be used to define the etchingpart and non-etching part. A mask or other chemical blocking materialcan be placed on the blocking layer with apertures defining where thechemical etch will occur. In one example, MOCVD deposition is used toform the VCSEL layers. In one example, the non-etching region is definedby placing a layer of SiO₂ everywhere on the blocking layer except forleaving the one or more holes (circular, trapezoidal or other shape) forthe region to be etched (e.g., trenches). Then the SiO₂ is removed.

Also, the active region or whole semiconductor layers of a VCSEL can beproduced with molecular beam epitaxy (MBE). Lower growth temperaturesduring the MBE can be used to prepare the VCSEL semiconductor layers.The growth of these structures by MBE can be performed at <(less than)500° C. Comparatively, the temperatures for MOCVD can be >(greater than)600° C. Additionally, the VCSELs can be prepared by methods that aresimilar to MBE, such as GSMBE (gas source MBE) and MOMBE (metalorganicMBE) or the like that can produce the regions as described.

The chemical etching can be any that is useful and known in the art.

One skilled in the art will appreciate that, for this and otherprocesses and methods disclosed herein, the functions performed in theprocesses and methods may be implemented in differing order.Furthermore, the outlined steps and operations are only provided asexamples, and some of the steps and operations may be optional, combinedinto fewer steps and operations, or expanded into additional steps andoperations without detracting from the essence of the disclosedembodiments.

The present disclosure is not to be limited in terms of the particularembodiments described in this application, which are intended asillustrations of various aspects. Many modifications and variations canbe made without departing from its spirit and scope, as will be apparentto those skilled in the art. Functionally equivalent methods andapparatuses within the scope of the disclosure, in addition to thoseenumerated herein, will be apparent to those skilled in the art from theforegoing descriptions. Such modifications and variations are intendedto fall within the scope of the appended claims. The present disclosureis to be limited only by the terms of the appended claims, along withthe full scope of equivalents to which such claims are entitled. It isalso to be understood that the terminology used herein is for thepurpose of describing particular embodiments only, and is not intendedto be limiting.

It will be understood by those within the art that, in general, termsused herein, and especially in the appended claims (e.g., bodies of theappended claims) are generally intended as “open” terms (e.g., the term“including” should be interpreted as “including but not limited to,” theterm “having” should be interpreted as “having at least,” the term“includes” should be interpreted as “includes but is not limited to,”etc.). It will be further understood by those within the art that if aspecific number of an introduced claim recitation is intended, such anintent will be explicitly recited in the claim, and in the absence ofsuch recitation no such intent is present. For example, as an aid tounderstanding, the following appended claims may contain usage of theintroductory phrases “at least one” and “one or more” to introduce claimrecitations. However, the use of such phrases should not be construed toimply that the introduction of a claim recitation by the indefinitearticles “a” or “an” limits any particular claim containing suchintroduced claim recitation to embodiments containing only one suchrecitation, even when the same claim includes the introductory phrases“one or more” or “at least one” and indefinite articles such as “a” or“an” (e.g., “a” and/or “an” should be interpreted to mean “at least one”or “one or more”); the same holds true for the use of definite articlesused to introduce claim recitations. In addition, even if a specificnumber of an introduced claim recitation is explicitly recited, thoseskilled in the art will recognize that such recitation should beinterpreted to mean at least the recited number (e.g., the barerecitation of “two recitations,” without other modifiers, means at leasttwo recitations, or two or more recitations). Furthermore, in thoseinstances where a convention analogous to “at least one of A, B, and C,etc.” is used, in general such a construction is intended in the senseone having skill in the art would understand the convention (e.g., “asystem having at least one of A, B, and C” would include but not belimited to systems that have A alone, B alone, C alone, A and Btogether, A and C together, B and C together, and/or A, B, and Ctogether, etc.). In those instances where a convention analogous to “atleast one of A, B, or C, etc.” is used, in general such a constructionis intended in the sense one having skill in the art would understandthe convention (e.g., “a system having at least one of A, B, or C” wouldinclude but not be limited to systems that have A alone, B alone, Calone, A and B together, A and C together, B and C together, and/or A,B, and C together, etc.). It will be further understood by those withinthe art that virtually any disjunctive word and/or phrase presenting twoor more alternative terms, whether in the description, claims, ordrawings, should be understood to contemplate the possibilities ofincluding one of the terms, either of the terms, or both terms. Forexample, the phrase “A or B” will be understood to include thepossibilities of “A” or “B” or “A and B.”

In addition, where features or aspects of the disclosure are describedin terms of Markush groups, those skilled in the art will recognize thatthe disclosure is also thereby described in terms of any individualmember or subgroup of members of the Markush group.

As will be understood by one skilled in the art, for any and allpurposes, such as in terms of providing a written description, allranges disclosed herein also encompass any and all possible subrangesand combinations of subranges thereof. Any listed range can be easilyrecognized as sufficiently describing and enabling the same range beingbroken down into at least equal halves, thirds, quarters, fifths,tenths, etc. As a non-limiting example, each range discussed herein canbe readily broken down into a lower third, middle third and upper third,etc. As will also be understood by one skilled in the art all languagesuch as “up to,” “at least,” and the like include the number recited andrefer to ranges which can be subsequently broken down into subranges asdiscussed above. Finally, as will be understood by one skilled in theart, a range includes each individual member. Thus, for example, a grouphaving 1-3 cells refers to groups having 1, 2, or 3 cells. Similarly, agroup having 1-5 cells refers to groups having 1, 2, 3, 4, or 5 cells,and so forth.

From the foregoing, it will be appreciated that various embodiments ofthe present disclosure have been described herein for purposes ofillustration, and that various modifications may be made withoutdeparting from the scope and spirit of the present disclosure.Accordingly, the various embodiments disclosed herein are not intendedto be limiting, with the true scope and spirit being indicated by thefollowing claims. All references recited herein are incorporated hereinby specific reference in their entirety.

1. Polarization-Controlled Single-Mode VCSEL, T. Yoshikawa, et al, IEEEJournal Of Quantum Electronics, Vol. 34, No. 6, 1998.

The invention claimed is:
 1. A VCSEL comprising: an elliptical oxideaperture in an oxidized region that is located between an active regionand an emission surface, the elliptical aperture having a short radiusand a long radius with a radius ratio (short radius)/(long radius) beingfrom about 0.6 to about 0.8, the VCSEL having a relative intensity noise(MN) of less than or about −140 dB/Hz; and one or more trenches lateralof the oxidized region, the one or more trenches forming an ellipticalshape, wherein the oxidized region has an elliptical shape.
 2. The VCSELof claim 1, further comprising an elliptical emission aperture havingsame dimensions of the elliptical oxide aperture.
 3. The VCSEL of claim2, further comprising an elliptical contact having an elliptical contactaperture therein, the elliptical contact being around the ellipticalemission aperture.
 4. The VCSEL of claim 3, wherein the ellipticalcontact is C-shaped.
 5. The VCSEL of claim 1 wherein the one or moretrenches are trapezoidal shaped trenches.
 6. The VCSEL of claim 5,further comprising a mesa having the elliptical oxide aperture, oxidizedregion, elliptical emission aperture, elliptical contact, and one ormore trenches in the elliptical shape.
 7. The VCSEL of claim 6, furthercomprising a contact pad and an electrical connector that electricallyconnects the contact pad with the elliptical contact.
 8. A plurality ofVCSELs, each VCSEL being the VCSEL of claim 1, the plurality of VCSELsbeing a group of VCSELs with a normal quantile of at least or about 0.9(90%) having at least a standard of acceptability.
 9. The plurality ofVCSELs of claim 8, wherein the plurality of VCSELs being a group ofVCSELs with the normal quantile of at least about 0.9 (90%) have the RINof less than or about −141 dB/Hz.
 10. The plurality of VCSELs of claim9, each VCSEL being on a single wafer.
 11. The plurality of VCSELs ofclaim 10, each VCSEL having the elliptical aperture having a shortradius and a long radius with a radius ratio (short radius)/(longradius) being from about 0.64 to about 0.7.
 12. A method of designing aVCSEL, the method comprising: preparing a plurality of VCSELs that eachhave an elliptical oxide aperture in an oxidized region that is locatedbetween an active region and an emission surface, an ellipticity of eachVCSEL being defined by a short radius and a long radius of theelliptical oxide aperture with a radius ratio (short radius)/(longradius) being from about 0.6 to about 0.8, the plurality of VCSELshaving a plurality of different radius ratios; operating the pluralityof VCSELs to emit light; testing each VCSEL for its relative intensitynoise (RIN); grouping each VCSEL into a group for a normal quantile of astandard of acceptability; and identifying at least one radius ratio fora normal quantile group of VCSELs having a RIN less than or about −140dB/Hz.
 13. The method of claim 12, wherein the preparing includesmanufacturing the plurality of physical VCSELs.
 14. The method of claim12, wherein the preparing includes digitally creating the plurality ofVCSELs to be simulated and the operating includes simulating emission oflight from the plurality of VCSELs.
 15. The method of claim 12, whereinthe normal quantile group is at least or about 0.9 (90%).
 16. The methodof claim 12, comprising recording and storing the identified at leastone radius ratio onto a non-transitory tangible medium.
 17. The methodof claim 16, comprising recording and storing the RIN and normalquantile for the identified at least one radius ratio into thenon-transitory tangible medium so as to be linked with the identified atleast one radius ratio.
 18. A method of manufacturing a VCSEL, themethod comprising: obtaining a radius ratio for an elliptical oxideaperture for a VCSEL having a relative intensity noise (RIN) of lessthan or about −140 dB/Hz; identifying a short radius dimension and alarge radius dimension for the radius ratio; preparing a VCSEL stack oflayers; oxidizing at least a portion of the VCSEL stack of layers toform the elliptical oxide aperture within a lateral oxidized region soas to have the radius ratio, short radius, and large radius; and formingone or more trenches lateral of the oxidized region, the one or moretrenches forming an elliptical shape, wherein the oxidized region has anelliptical shape.
 19. The method of claim 18, comprising: preparing andoxidizing a plurality of VCSELs to have the elliptical oxide aperturewithin a lateral oxidized region so as to have the radius ratio, shortradius, and large radius, the plurality of VCSELs being a group ofVCSELs having a normal quantile of at least or about 0.9 (90%) having orat least a standard of acceptability.